[Wien] Question about units of density in density plots

[Fecher, Gerhard]

Dear Peter,
I have a question about the units of the density when preparing 3d density plots
with prepare_xsf_lapw or 3ddens. For tests, I summed up the densities on a 201^3
mesh taken from the produced xsf files and received very different results.
(see below). Indeed, I did not expect absolutely correct values for the number
of electrons, but the values of the sums from prepare_xsf are larger and those 
from 3ddens are significantly lower.
Therefore, I wonder which units are used (e-/A^3 ?).

I used a simple cubic structure with 8 atoms and total 332 or 52 valence
electrons. The results for a meshsize of about 0.02 A (201^3 points,
dV=0.000008A^3) are after summation approximately:
- prepare_xsf tot=394.3  val=76.35 (was used with ANG)
- 3ddens tot=58.4 val=11.3
the ratio tot/val is equal for the two methods.
both, the tot and val, values from prepare_xsf are about 6.7 times larger 
compared to those from 3ddens.

What I try is to calculate the similarity of electron distributions. For this I
do not need the absolute values and so far the summations that I need are
independent on the method after normalisation as also seen from the tot/val
ratio.
(Actually this was a test, and indeed, the core electrons used in tot are
localised closer to the nuclei and one may not hit all of them completely.)

Just a remark: I realized that prepare_xsf produced some thousand files that are
not removed with clean_lapw, is it possible to open all those files (*.def etc.)
in the script (under def_write_XXX) and may be at other places as SCRATCH
instead of UNKNOWN, such that they are deleted automatically after each run?

Sometimes it would be helpful if clean_lapw did not only delete all large but
also all empty files, or are some empty files (e.g. after scf) still needed
later? e.g. using (maybe with an additional switch -e):
  find . -type f -size 0 -delete
  find . -type f -empty -delete
  rm -rf $(find . -maxdepth 10 -type f -empty)
or something similar ?
(Indeed, one can change clean_lapw every year by oneself ;-))

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Physics
Johannes Gutenberg - University
55099 Mainz
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